1. Field of Invention
This invention pertains to method and apparatus for recording information on storage media, and particularly to method and apparatus for transporting and reeling storage media in a helical scan recording system.
2. Related Art and Other Considerations
Numerous prior art patents and publications teach recording and reading of information stored in helical stripes (or "tracks") on magnetic tape. Examples of helical scan tape drives are shown, inter alia, in the following U.S. patents (all of which are incorporated herein by reference):
U.S. Pat. No. 4,835,628 to Hinz et al.
U.S. Pat. No. 4,843,495 to Georgis et al.
U.S. Pat. No. 5,065,261 to Hughes et al.
U.S. Pat. No. 5,068,757 to Hughes et al.
U.S. Pat. No. 5,142,422 to Zook et al.
In a helical scan arrangement, travelling magnetic tape is at least partially wrapped around a rotating drum so that heads (both write heads and read heads) positioned on the drum are contiguous to the drum as the drum is rotated. One or more write heads on the drum physically record data on the tape in a series of discrete stripes oriented at an angle with respect to the direction of tape travel. The data is formatted, prior to recording on the tape, to provide sufficient referencing information to enable later recovery during readout by one or more read heads.
In many prior art helical scan systems, a fixed-radius, capstan is provided to control the linear motion to the tape as the tape travels past the drum. The capstan is driven by a dedicated capstan motor. In capstan systems, a tachometer is typically provided on the capstan to provide feedback information for ensuring constant linear velocity of the tape.
Other helical scan systems (known as "reel-to-reel) do not employ a capstan. Once example of a "reel-to-reel system is disclosed in U.S. Pat. No. 4,125,881 to Eige et al. (incorporated herein by reference). One reel of such a system is typically known as a "supply" reel, the other reel is typically called a "take-up" reel. The supply reel and take-up reels generally each have dedicated motors. Various one-half inch magnetic tape products (such as IBM model 3480) are reel-to-reel streamers with stationary heads or linear tracking.
Generally, prior art capstanless systems involved high speed and high tension operating conditions and a stationary head. Prior art capstanless systems accordingly are inapplicable to helical scan products such as those using 4 mm or 8 mm magnetic tape or other low speed drives generally.